1. Field of the Invention
The present invention relates to a method and device for supplying bags to which spouts are to be attached, in which the method and device are applied to a bag supply process when bags to which spouts are to be attached are supplied to left and right grippers of a spout attachment device.
2. Description of the Related Art
Japanese Patent No. 3,261,543 discloses a method for manufacturing a spout equipped bag (a bag equipped with a spout). In this method, bags (bags filled with contents therein, in this art) that have been positioned in a horizontal orientation within an empty bag storage device are switched to a vertical orientation, in which the bag mouth faces upward, and then the bags are supplied to a plurality of pairs of left and right grippers that are provided at a regular spacing along a circular movement path; and further the bags are moved intermittently along the movement path, and then they are intermittently transferred along with the movement of the grippers while the corner part of the mouth part of each one of the bags is cut at an angle, a spout is attached to the corner opening that is angled after being cut, and then a nozzle is inserted into the horizontal portion of the bag mouth to fill the bag with a liquid or content. A spout that is to be attached to the angled corner part of a bag whose basic shape is square is called a corner-spout, and this bag to which a corner-spout is to be attached is called a corner-spout attachment bag.
Japanese Patent Application Laid-Open (Kokai) No. H7-187202 discloses a method for manufacturing a spout equipped bag (a bag filled with content therein, in this art); and in this method, bags that have been taken out of an empty bag storage device are supplied in a substantially vertical orientation, in which the bag mouth faces upward, to the grippers of a bag transfer device having a plurality of pairs of left and right grippers that are provided at a regular spacing along a circular movement path and are moved intermittently along this movement path; and then these bags are intermittently transferred along with the movement of the grippers while a nozzle is then inserted into the bag mouth of each one of the bags so as to fill the bag with a liquid, and then a spout is attached to the center part of the bag mouth which is set horizontally. A spout that is to be attached to the center part of a bag mouth which is substantially parallel to the width direction of the bag whose basic shape is square is called a center-spout, and this bag to which such a center-spout is to be attached is called a center-spout attachment bag.
Japanese Patent No. 4,566,628 describes how a spout (a corner-spout) is attached to the angled mouth of a corner-spout attachment bag, in which the bag is inclined so that the bag mouth is set horizontal and facing upward, and this inclined corner-spout attachment bag is supplied in this state to a spout attachment device. Japanese Patent No. 5,112,770 describes how a spout (a corner-spout) is attached to the angled mouth of a corner-spout attachment bag, in which the corner-spout attachment bag is set in a horizontal orientation, rotated by a specific angle in this state, and then supplied to a spout attachment device.
The methods for manufacturing a spout equipped bag disclosed in Japanese Patent No. 3,261,543 and Japanese Patent Application Laid-Open (Kokai) No. 117-187202 differ in the order of the spout attachment step and the filling step; however, they are same in that the two side edges of a bag are gripped by grippers, the bag is held hanging down with its mouth facing upward, and then the bag is intermittently transferred while a spout is attached to a specific location of the bag mouth during this transfer. Therefore, it can be easily understood that theoretically, the attachment of a corner-spout and the attachment of a center-spout can be performed by the same spout attachment device (a spout equipped bag manufacturing apparatus). It can also be easily imagined that in this spout attachment device (a spout equipped bag manufacturing apparatus), if the portion of process related to spout attachment is stopped, ordinary flat bags and self-standing bags (both without spouts) can be filled and packaged.
However, if the attachment of a corner-spout and the attachment of a center-spout are performed by the same spout attachment device (or by the same spout equipped bag manufacturing apparatus), in actual practice the following problems are encountered.
(1) The form of the bag mouth and the direction in which the spout is supplied are different when attaching a corner-spout from when attaching a center-spout. More specifically, in a corner-spout attachment bag (a bag to which a spout is to be attached to its upper corner portion), the corner opening to which the spout is attached is set angled, and the spout is supplied from diagonally upward. In a center-spout attachment bag (a bag to which a spout is to be attached to its upper center portion), the bag mouth to which the spout is attached is set horizontal, and the spout is supplied to or inserted into the bag from straight up in the vertical direction. Therefore, it is impossible to use a shared or common spout insertion device or spout sealing device to attach both corner-spout and center-spout. It is conceivable that these devices could be replaced when attaching a corner-spout and when attaching a center-spout; however, this replacement work leads to a decrease in productivity.
(2) In the manner of corner-spout attachment disclosed in Japanese Patent No. 3,261,543, as in the case of center-spout attachment disclosed in Japanese Patent Application Laid-Open (Kokai) No. H7-187202, the two side edges of a bag are gripped so that the center line (a straight line passing through the center of the bag in its width direction) of the bag in the left and right grippers is vertical; however, because the corner part of the bag is cut at an angle, the position of the bag with respect to the grippers is higher than when attaching a center-spout. Meanwhile, the surface level of the liquid that has been filled in a bag must be lower than the bottom edge of the grippers. This is because if the surface level of the liquid is above the lower edge of the grippers, the liquid spills out of the bag mouth when spacing of the left and right grippers is increased and the bag mouth is pulled taut prior to being sealed. Therefore, even with bags of the same size, the maximum amount to which a bag can be filled with a liquid is smaller when attaching a corner-spout than when attaching a center-spout, and the volume of the inside of the bag cannot be fully taken advantage of. This means that a bag one size larger may have to be used in some cases.
(3) When a corner-spout is attached, as disclosed in Japanese Patent No. 4,566,628, if a corner-spout attachment bag is inclined so that the corner opening to which the spout is attached is horizontal, and the bag is supplied in this state to the grippers, then the direction in which the spout is supplied to the corner-spout attachment bag can be made vertical as in the case of attaching a center-spout, and also the height position of the corner-spout attachment bag with respect to the grippers can be substantially the same as the height of a center-spout attachment bag. Therefore, the problem discussed in (1) and (2) above can be more or less solved.
Nevertheless, if a corner-spout attachment bag is inclined (rotated along the bag surface) so that the corner opening becomes horizontal and supplied in this state to the left and right grippers, there will be such a problem that the spout attachment device is offset in the horizontal direction from the attachment position of the center-spout (usually in the center of the bag mouth opening). This will be described below with reference to FIGS. 11A through 12B.
First, such a situation is considered that a center-spout attachment bag is positioned in a horizontal orientation at a specific position in a magazine, after which this center-spout attachment bag is supplied to a spout attachment device, and then a spout is attached in the center of the opening at the mouth of this bag. In a center-spout attachment bag, three sides there of are sealed. In this case, as shown in FIG. 11A, a center-spout attachment bag 1 is positioned horizontally at a specific location in the magazine, the bag is picked up at its surface by a suction cup (not shown), and then the bag q is transferred forward to a specific location along the lengthwise direction of the bag as shown in FIG. 11B. This center-spout attachment bag 1 is then picked up again by another suction cup or held by a chuck, switched to a vertical orientation, and transferred to the left and right grippers of the spout attachment device.
In this transfer process, a single vertical plane is set as a reference plane (the reference plane N), and the center line C in the lengthwise direction of the center-spout attachment bag 1 positioned in the magazine (the straight line that passes through the center of bag 1 in its width direction) is set in the reference plane N. The center line C of the bag does not leave this reference plane N when the center-spout attachment bag 1 is transferred from the specific location in the magazine to the grippers.
Next, another situation is considered that a corner-spout attachment bag, instead of the center-spout attachment bag 1, is positioned at a specific location in a magazine, after which this corner-spout attachment bag is supplied to a spout attachment device, and a spout is attached in the center of the corner opening of the bag. As shown in FIG. 12A, the corner-spout attachment bag 2 is positioned so that the center line C along the lengthwise direction of the bag lie in the reference plane N. In this case, just as in the center-spout attachment bag 1 described above, the positioned corner-spout attachment bag 2 is picked up at its surface by a suction cup and transferred forward, and the suction cup is rotated so that the corner opening 3 of the corner-spout attachment bag 2 face perpendicular to the transfer direction of the corner opening 3 during this transfer process. The rotational angle of the suction cup is the same as the inclination angle θ of the corner opening 3 of the bag 2. The rotational axis O of the suction cup that picks up the corner-spout attachment bag 2 is set to be on the center line C (the reference plane N) along the lengthwise direction of the bag 2, and the rotational axis O is moved over the reference plane N along with movement of the suction cup.
In this example, as shown in FIG. 12B, the corner-spout attachment bag 2 is such that a corner opening vertical line M (a straight line that passes through the center of the corner opening 3 and is perpendicular to the corner opening 3) and the reference plane N are offset by spacing S. Also, even if there is no change in the position of the rotational axis O of the suction cup when it has picked up the corner-spout attachment bag 2 that has been positioned in the magazine, the value of the spacing S will fluctuate variously if the width of the corner-spout attachment bag 2, the inclination angle θ of the corner opening 3, or the length L of the corner opening 3, is different.
Accordingly, when the attachment of a center-spout and the attachment of a corner-spout are performed by the same spout attachment device, a spout insertion device and a spout sealing device that are adjusted for the attachment of a center-spout cannot be used just as they are for attaching a corner-spout, and therefore, either these devices have to be replaced or their positions have to be adjusted, etc., so as to accommodate the attachment of a corner-spout, and this work greatly diminishes the productivity of the spout attachment device. Also, replacing these devices, adjusting their positions and so forth also have to be performed if there is a change in the width of corner-spout attachment bags, the inclination angle θ of the corner opening 3 or the length L of the corner opening 3.